There are in the prior art a number of ankle braces which have been developed for protecting the ankle from damage or for providing protection and support for an ankle fracture. In the latter case, devices such as shown in the Crispin U.S. Pat. No. 4,771,768 the Biedermann U.S. Pat. No. 4,834,078 and Spencer U.S. Pat. No. 4,630,600 have been developed to control the motion of the leg with respect to the foot to permit the injured ligaments or ankle fracture to heal. These devices are used when a plaster cast is removed from an injured ankle joint so as to provide some degree of freedom of movement.
There are prior art devices which are designed to provide support for the ankle to brace the ankle against lateral sprains. Examples of such devices are the Craythorne U.S. Pat. No. 4,865,023 and Robinson U.S. Pat. No. 4,922,630. The Craythorne provides a heel plate together with a bracing pad comprising an ankle cuff which fits around the leg portion and provides a method for bracing the ankle but does not permit sufficient angular motion of the ankle joint. The Robinson U.S. Pat. No. 4,922,630 provides an inversion resisting device which does permit motion in eversion, plantar flexion and dorsi flexion. The device provides a leg engaging strap which is connected to the shoe by a strapping mechanism.
Other patents showing various types of ankle support structures are the Sproaken U.S. Pat. No. 4,425,721, Rathmell U.S. Pat. No. 3,775,872, Ottieri U.S. Pat. No. 4,955,149 and Grim U.S. Pat. No. 4,869,267. All of these prior devices are designed to protect the ankle by limiting the degree of movement of the leg with respect to the foot so as to protect the ankle from fracture or sprains.